There are a number of devices that have been used for transportation over the snow. These include skis, sleds and the like.
Many of these have been motorized. Snowmobiles are of course the most popular form of motorized snow transportation. There have also been a number of devices designed to attach to skis and sleds and the like. Some of these include Kallio U.S. Pat. No. 2,706,528, Walsh U.S. Pat. No. 3,146,840, Lichfield U.S. Pat. No. 3,509,955, Gremerei U.S. Pat. No. 3,568,787, Raistakka U.S. Pat. No. 3,757,249, Gerich U.S. Pat. No. 3,707,199.
A power ski device is disclosed for example in Thompson U.S. Pat. No. 3,710,888. A backpack propelling device is disclosed in McLeod U.S. Pat. No. 3,809,173. Other ski mounted devices include Husted U.S. Pat. No. 3,853,192, Husted U.S. Pat. No. 3,964,560, Shiber U.S. Pat. No. 3,966,010, and Husted U.S. Pat. No. 4,035,035. Snowmobile type devices are disclosed for example in Condon U.S. Pat. No. 4,234,050 and Shelton U.S. Pat. No. 4,307,788. Most of these snowmobile type devices include drive belts which are cleated in some way or corrugated to provide a snow engaging or ground engaging surface. Since they are corrugated they do not slide over the ground but are merely a form of propulsion. Husted U.S. Pat. No. 3,964,560 discloses an endless belt that has a plurality of inwardly projecting spokes that engage the ground at an angle and are described as automatically disengaging from the snow and flatten out against the belt during a powerless skiing mode. However, these do not provide the action of a drive cleat engaging the snow. Further, these can easily become bound with snow and provide little positive traction.
These devices which either mount to skis generally require hand control of the throttle. This can be particularly inconvenient and does not permit the rider full use of his arms to assist in balancing.